A memristor is a two-terminal electrical device that may function as a passive current limiter in which an instantaneous resistance state is a function of bias history. Specifically, an electrical flux or a time integral of the electric field, between terminals of the memristor is a function of the amount of electric charge, or a time integral of a current, that has passed through the memristor. As such, a memristor represents a two-terminal device that effectively has a memory of its ‘state’ (e.g. resistance) that is a function of its bias history. Moreover, the bias history is solely dependent on the amount of electric charge that has passed through the device. In other words, a resistance of a memristor may be changed by applying a programming signal to the memristor (e.g., by applying a voltage across the two terminals and passing a current through the memristor), for example.
Notably, memristors may be switched between ‘states’ (e.g., using the programming signal) and therefore are potentially useful as programmable circuit elements for a variety of memory circuits and related applications. Moreover, the programmed state of the memristor is maintained without power such that memristors may function as inherently non-volatile memory elements. For example, a memristor may be switched by a programming signal between an ‘ON’ state and an ‘OFF’ state effectively implementing a binary memory cell or element. In another application, the memristor may be switched or programmed to assume any one of several intermediate states between the ON state and the OFF state using the programming signal. Moreover, the memristor may be used to record and retain an analog level facilitating its use in circuits such as neural networks.
Unfortunately, memristors may occasionally develop a short circuit as a result of being switched between states by the programming signal. The short circuit effectively results in the memristor becoming trapped or stuck in an ON state or condition. Such a ‘stuck on’ state of a short circuited memristor effectively renders the memristor unusable as a programmable circuit element. Moreover, a short circuited memristor may also interfere with the operation of other memristors. For example, a short circuited memristor connected in parallel with a plurality of other memristors by a common connection (e.g., a bit line) may effectively prevent accessing the other memristors. The short circuit may effectively ‘short out’ the bit line such that access to individual ones of the other memristors is no longer available, for example.
Certain embodiments of the present invention have other features that are one of in addition to and in lieu of the features illustrated in the above-referenced figures. These and other features of the invention are detailed below with reference to the preceding drawings.